The present invention can be used in many different engaging systems such as hay tools, rakes, pickups, etc but is particularly applicable both for swathers or windrowers where the header is carried on a swather tractor and for combine harvesters where the header is carried by a combine adapter connected to the feeder house. If used for cutting crop for harvesting, the header can use different cutting systems including sickle bars and rotary mowers or like cutting arrangements.
Most windrowers on the market all have some type of hydraulic header flotation. These types of flotation systems suspend the header from the windrower so that there remains a small percentage of the header mass supported by the ground. The advantages to these types of hydraulic float systems include the ability to easily adjust to a wide range of header weights/types, full adjustability of flotation system from the cab, few moving parts, compact, has built in dampening effects and is well received in the market.
In the traditional hydraulic float systems, the header float cylinders are connected to a respective accumulator, pressure sensor and pressure control valve. The pressure control valves are in turn connected to a hydraulic pressure source such as a load sense pump. The controller receives input signals from the pressure sensors and makes adjustments to the pressure control valves to maintain a known pressure in the accumulator/cylinder circuit. The accumulator/cylinder system acts much like a spring so that when the header hits an obstacle and needs to go over the obstacle, the accumulator supplies pressure and flow to the cylinder to aid the movement of the header. When the header needs to go down into a ditch or low spot, the float cylinder drives oil back into the accumulator.
The assignees of the present application, MacDon, has traditionally maintained a coil spring flotation system that typically has better ground following capabilities. A typical MacDon spring flotation system can achieve ground pressure in the order of 10% of the header mass while still having acceptable ground following capabilities. The spring flotation systems are currently used on MacDon windrowers and combine adapters.
Typical combine harvesters have an arrangement in which the header is fixedly mounted to the feeder house and hence cannot float on the ground but instead is controlled in position by movement of the feeder house. This includes up and down movement of the height of the header and also twisting movement about a generally forwardly extending axis obtained by twisting a front face plate of the feeder house to which the header is mounted, about the axis longitudinal of the feeder house.